Shinshu, Japan – May 15, 2025 — New research from Shinshu University suggests that strong mother-infant bonding may help buffer children against the long-term emotional and behavioral effects of postpartum depression.
While the importance of maternal mental health and early bonding in a child’s development is well-established, few studies have examined how these two factors interact to influence outcomes in middle childhood. A recent study led by Associate Professor Daimei Sasayama and Professor Hideo Honda of Shinshu University’s School of Medicine sheds new light on this complex relationship.
Published on April 15, 2025, in the Archives of Women’s Mental Health, the study found that while postpartum depression can negatively impact children’s emotional and behavioral health by sixth grade, early secure bonding between mother and infant significantly mediates this effect.
Study Design and Key Findings
The study followed 245 mother–child pairs in Okaya, Japan, whose children were born between April 2009 and April 2012. Researchers used standardized tools including the Edinburgh Postnatal Depression Scale (EPDS) to assess depressive symptoms in mothers, and the Mother-to-Infant Bonding Scale–Japanese version (MIBS-J) to evaluate early bonding. Children’s emotional and behavioral health was later assessed in sixth grade using the Strengths and Difficulties Questionnaire (SDQ), completed by both children and their caregivers.
Data collection began in the immediate postpartum period, between two weeks and one month after birth. The majority of caregivers completing the SDQ were mothers (92.2%), with fathers (7.3%) and one additional caregiver also participating.
Results revealed that 17.1% of mothers exhibited postpartum depressive symptoms, aligning with national prevalence rates in Japan. These symptoms were significantly associated with later psychosocial difficulties in their children, both directly and indirectly through impaired bonding.
Crucially, the researchers found that mother-infant bonding mediated approximately 34.6% of the impact of maternal postpartum depression on child difficulties. Boys were found to be particularly vulnerable, showing higher levels of conduct problems and hyperactivity or inattention.
“Our findings confirm that early bonding can partially shield children from the long-term effects of postpartum depression,” said Dr. Sasayama. “This emphasizes the critical role that secure early attachment plays in healthy emotional and behavioral development.”
Implications for Intervention
The research underscores the need for early interventions that support mother-infant bonding in the context of postpartum depression. Such interventions, experts say, could significantly improve child outcomes by addressing issues before they evolve into long-term challenges.
“Understanding the mediating role of bonding opens the door to more targeted support strategies for mothers experiencing postpartum depression,” said Dr. Sasayama. “Future studies should explore which depressive symptoms most strongly affect bonding and incorporate additional variables such as genetics, socioeconomic status, and family dynamics.”
Looking Ahead
The team calls for larger studies to further examine the underlying mechanisms that influence the interplay between maternal mental health, early bonding, and child development. Integrating biological and social factors may help researchers design more effective interventions tailored to diverse family needs.
As mental health continues to gain prominence in public health discussions, the findings from this study contribute valuable insight into how early-life experiences shape children’s long-term well-being—and how timely, supportive actions can make a lasting difference.
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